Fire Safety with Lithium and Lithium Ion batteries

[goninanbl00d]

Excellent thread.
I have a question about the salt water though. Wouldn't it be dangerous to put a lithium battery into water? I'm no professional, but it seems like a bad idea to me.

Oh, sorry. I didn't see this. Apologies.

The battery should be sealed so no water should enter the battery, however, batteries do leak with age. There's no way to be sure that it doesn't leak.

Best idea is to allow them to cool, then take them to a battery recycling centre.

 

[JaiNobeZ]

I watched a video once where someone dropped a bundle of Lithium (i think it was Lithium and not Lithium ion) batteries into a bucket of salt water, and they exploded.

Salt water, i'm relatively sure, is a pretty good conductor. The charged ions move back & forth picking up & dumping electrons at the relevant locations. Seems to me that if you really do have to discharge them, it would be best to do it in de-ionised, or at the very least, tap water so that it's a less good conductor and doesn't discharge the batteries too quickly.

But i might be wrong.

 

[ludwigfan]

Haha I depose of my lithium primaries in an environmentally friendly, responsible and intelligent way.

I heat them strongly with a blow torch resulting in a them making a loud bang and flames

Yeah I'm a retard

I've always wanted to recharge them by securing them to a model rocket and firing them at storm clouds.

 

[JaiNobeZ]

I have a problem. I'm a brit (insert fish-and-chips and teapot jokes here), and us brits have square-pin plugs. I've received 2 CR123 chargers from Rayfoss with the american two flat-pin plugs and here's where the problem sets in.

They fit into my adaptor either way round. So i now don't know which way round to stick them and whether something will explode if i do it wrong.

Any help, anyone?

 

[goninanbl00d]

It's AC, so the voltage changes 50 (or was it 60) times a second.

So either way, it doesn't matter, because the voltage alternates from +220 to -220.

 

[Things]

The AC sinewave has 220/240V peaks on either side. Most battery chargers use a simple diode rectifier and filtering capacitor combination, so it doesn't matter which polarity you feed it with. You'll find this a lot with those AC plugs that look like the figure 8, some people get really confused about plugging it in the right way.

 

[ludwigfan]

While the polarity doesn't matter, the voltage does. We have 120V AC here in the states and in Europe they have 240. So either the charger will have to convert or you will need a transformer. Verify that the charger is suitable for 240VAC 50Hz before plugging it in unless you want to convert the charger into a smoke machine.

 

[JaiNobeZ]

Lol thanks guys, but i did all those things and the charger still went bang. Peice of shit. Luckily it didn't have any batteries in it at the time.

 

[flogged]

There's a relatively new lithium battery chemistry that's now making significant 'commercial' inroads. Lithium Iron Phosphate.
Lithium iron phosphate battery - Wikipedia, the free encyclopedia

The energy density is not quite as high as Li-ion, however LFP batteries have two big advantages over Li-ion. First they have a much longer shelf life, and they can handle many more charge/discharge cycles. Second they are much less prone to exploding. Safety and all that.

I believe Tenergy (and others) are now offering these batteries in various common sizes, like CR2 and CR123

 

[Benm]

I suppose explosion risk and energy/power density are always related. This problem is by no means new for lithium batteries - back in the day NiCd batteries could melt themselves and even catch fire when short circuited. Their energy density is not that high, but the power density is - all the energy is released in a few minutes in such cases.

Increased life would be a good thing though, since that it what actually kills most lithium batteries. Especially laptop batteries suffer from this, going down to half capacity in a year or two, far under the technical life of the laptop itself.

 

[JaiNobeZ]

I suppose explosion risk and energy/power density are always related. This problem is by no means new for lithium batteries - back in the day NiCd batteries could melt themselves and even catch fire when short circuited. Their energy density is not that high, but the power density is - all the energy is released in a few minutes in such cases.

Increased life would be a good thing though, since that it what actually kills most lithium batteries. Especially laptop batteries suffer from this, going down to half capacity in a year or two, far under the technical life of the laptop itself.

My laptop battery currently has half an hour from fully charged. My charger's busted so now idk what i'm going to do...

I emailled Rayfoss and they said they'd send me a new CR123 charger, incase anyone's interested. And she also said she's going to find a source of chargers with a British plug so starting now Rayfoss will send out chargers with the right plugs with orders.


Back on topic, would discharging them in salt water be a stupid idea or not? Like i said, my feeling is it would.

 

[vk2fro]

Just as a example, this is what happens when a lipo goes up. You dont want this happening inside:



Thats a large lipo battery - the kind used in model helicopters; but one cell is still enough to start a good fire!

And heres a similar incident in one of those bags



Dont cheap out if your buying one - theres another video on youtube with a test of a 99c ebay bag. The bag burst into flames. A paper bag would have been better protection

I've got big batteries for my helicopter in a small apartment. I use the bags not only for charging on my back patio, but to store the batteries inside under the laundry tub. Its all metal there so if something were to happen, i just get a very smokey laundry/bathroom, and the smoke alarm I put in there would make a racket. FWIW i have the "Lipo-Sack" brand which were the first ones to come out from memory.

The bags are plenty big enough to stuff a complete 18650 charger inside with two batteries, and many more if your not charging. (dont keep all your eggs in one basket!)

 

[Benm]

Back on topic, would discharging them in salt water be a stupid idea or not? Like i said, my feeling is it would.

Well, it wouldn't have to be that stupid as long as you are completely certain the cells are sealed and no water could leak in.

But its also entirely pointless: If you want to discharge a cell to zero volts, just connect a suitable resistor between postive and negative, and leave it be until its empty. This accomplishes the exact same thing as the salt water would, but without the risk of contact between lithium and water.

If you are concerned with explosion due to over-discharge, i'd recommend doing this somewhere outside. Its best to do it on a stone surface (like a terrace, or path made of sidewalk tiles), and cover it up with a nonglazed flower pot.

The flower pot may seem silly, but those are actually very good containers for extremely hot materials. In chemistry demonstrations we lit up thermite in common flower pots, resulting in a flow of liquid iron from the little hole in the bottom. I've never seen a pot break in that experiment, despite the reactants reaching temperatures over 2000 C.

 

[JaiNobeZ]

As was suggested already, why not blow them up from a safe distance before disposing, thus saving the need for either salt water or a resistor?

 

[Heirophant]

wow. scary and convincing but if i'm charging a 18650 for my rayfoss 200mW hand-held, do I really have a big risk of fire/explosion ?
wow.
i should charge outside maybe .
i will go get some sand and salt to keep near charging area.

 

[Benm]

The risk isnt as great as people make it to believe really.

The problem is not so much in the tiny chance as it is in the huge consequeces involved. Perhaps the probability is one in a mllion, but are you willing to take a one in a million chance of your home burning to the ground?